package com.yangg.designPattern.Flyweight;


import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Vector;

import com.mysql.jdbc.Connection;
/**
 * 
 * @author master-hadoop
 *享元模式
 *享元模式的主要目的是实现对象的共享，即共享池，当系统中对象多的时候可以减少内存的开销，通常与工厂模式一起使用。
 */
//数据库连接池
public class ConnectionPool {  

private Vector<Connection> pool;  

/*公有属性*/  
private String url = "jdbc:mysql://localhost:3306/test";  
private String username = "root";  
private String password = "root";  
private String driverClassName = "com.mysql.jdbc.Driver";  

private int poolSize = 100;  
//这里对instance可以使用一个单例模式
private static ConnectionPool instance = null;  
Connection conn = null;  

/*构造方法，做一些初始化工作*/  
private ConnectionPool() {  
    pool = new Vector<Connection>(poolSize);  

    for (int i = 0; i < poolSize; i++) {  
        try {  
            Class.forName(driverClassName);  
            conn = (Connection) DriverManager.getConnection(url, username, password);  
            pool.add(conn);  
        } catch (ClassNotFoundException e) {  
            e.printStackTrace();  
        } catch (SQLException e) {  
            e.printStackTrace();  
        }  
    }  
}  

/* 把连接对象返回到连接池 */  
public synchronized void release() {  
    pool.add(conn);  
}  

/* 返回连接池中的一个数据库连接 */  
public synchronized Connection getConnection() {  
    if (pool.size() > 0) {  
        Connection conn = pool.get(0);  
        pool.remove(conn);  
        return conn;  
    } else {  
        return null;  
    }  
}  
}